Early manifold on late Engine?

[RGBJavelin]

I know the deck height is taller on 70-up V-8s and the bolt holes in the center are a little different. Does an Early (pre 70) manifold have to be machined to fit properly on a late (70-up) engine?
I can drill out the center bolt holes, using the valey pan/Manifold gasket as a guide, which has both patterns, but is the angle of the surface of the manifold to the head going to be correct?
I ran a Torker on my 401 that had the holes opened up, but I got it that way, so I am not sure if that manifold originally was for early or late, and I am unaware if it was machined. But I never had any problems and the ports were pretty much matched up.
I now have an Offy, with part #5771, the holes are untouched, and I want to put it on my 70 304. I thought I read somewhere about using a late manifold on an early engine that machining was required, but does that go for an early manifold on a late engine? Will the end rail gaskets seal right?
For some reason I am not being able to picture all of the geometry going on in my head, If someone could just break it down for me with a general explaination??? :confused:

[javelinjeff]

last i remember it does not work

[RGBJavelin]

I am pretty sure, once the inner intake bolt holes are matched to the Gasket/Valley pan, that the manifold will fit either Early (67-69) or later (70-up) engines. I am wondering about the proper alignment of the head surface to the surface of the manifold. Just as if one was to have the heads shaved for higher compression, what kind of tolerence is acceptable for a proper fit and can this be corrected by using a thicker manifold gasket or something? Or is the difference so much that machining would be required? Ya know what I am trying to say here? :confused: